Method of making a slotted gas burner head



June 2, 1970 J. M. DUNSTON 3,514,333

METHOD OF MAKING A SLO'RTED GAS BURNER HEAD Filed April 15, 1968 2 Shets-Sheet l Filed April 15. 1968 June 2, 1970 J. M. DUNSTON 3,514,833

METHOD OF MAKING A SLOTTED GAS BURNER HEAD 2 Sheets-Sheet 2 United States Patent 3,514,833 METHOD OF MAKING A SLOTTED GAS BURNER HEAD James M. Dunston, Natick, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed Apr. 15, 1968, Ser. No. 721,228 Int. Cl. B21d 53/00 US. Cl. 29-157 6 Claims ABSTRACT OF THE DISCLOSURE SPECIFICATION The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a method of making a slotted gas burner head of the type used in atmospheric gas burners, such as the burners used in field ranges and the like, and to the resulting slotted gas burner head.

In outdoor camping activities and military field operations, pressurized liquid fuel burners are often used for heating and cooking purposes. Such burners range in size from very compact stoves having a capacity of about 2,500 B.t.u. per hour for use by individuals or small groups to relatively large and complex burner units used by the military in cooking and baking for large groups, such as the Burner Unit, Gasoline Feld Range Out-fit described in Military Specification MILaB40098 (QMC), dated Dec. 24, 1959, which has a capacity of about 55,000 Btu. per hour. The greater the capacity of such burner units the more important it is to provide for a uniform dispersion of a high volume of combustible vapors over a large surface area. In the type of burner unit shown in the above-mentioned military specification this is accomplished by providing a burner head having a hub and a plurality of arms extending outwardly therefrom. Each arm is provided with a large number of slots of as nearly uniform width as possible through which combustible vapors are fed to the combustion zone above the burner head.

In the past, it has been customary to cast the burner heads out of steel and cut the slots in the top surfaces of the burner heads. A gang of metal saws lined up in parallel were used to cut all of the slots in one or two arms of the burner head in a single cutting operation. However, this procedure has proven quite expensive since the metal saws are subject to damage by abnormally hard spots in the casting or as a result of the actions of inexperienced operators in bringing the rotating metal saws against the burner head surfaces too rapidly. When damage or dulling of one or more blades occurs it is necessary to disassemble the gang of saws and replace those that are unfit for further use. This results in 'frequent and sometimes prolonged periods of idlenessof the cutting machine, much labor in replacing damaged saws, and high costs for replacement metal saws.

It is therefore an object of the present invention to provide a method of making a slotted gas burner head 3,514,833 Patented June 2, 1970 "ice which avoids the above-mentioned disadvantages of the prior art method of making slotted gas burner heads.

Another object of the invention is to provide a method of making a slotted gas burner head which avoids the cutting of slots in metal burner heads by means of metal saws.

A further object of the invention is the provision of a slotted gas burner head having one or more arcuate slotted members detachably mounted on a base member.

Various other objects and advantages derived from the invention will be apparent from the following description of tWo embodiments of the invention, and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

The foregoing objects are accomplished by forming a helical coil of predetermined diameter from a metal strip having a rectangular cross-section in a manner such that the turns of the coil are spaced apart a predetermined substantially uniform amount, mounting a plurality of straight metal bars longitudinally of the coil in spaced parallel relation, joining the straight metal bars to each turn of the coil, cutting the coil and the bars along an approximately median longitudinal line in the bars to form a plurality of arcuate members having a plurality of spaced slots of substantially uniform width, and mounting the arcuate members on a base member having means for conducting gas to the slots in the arcuate members.

The present invention may be more fully understood by reference to the accompanying drawings wherein like reference characters designate like parts in the various views, and in which:

FIG. 1 is a side elevation, partially in section, of one of the arms of a multiple armed gas burner head made in accordance with the present invention;

FIG. 2 is a vertical sectional view of the arm of the gas burner head shown in FIG. 1 taken along the line 2-2 of FIG. 1;

FIG. 3 is a side elevation of a helical coil wound upon a mandrel with a plurality of straight metal bars held in spaced parallel relation longitudinally of the helical coil;

FIG. 4 is a vertical section taken along the line 44 of FIG. 3;

FIG. 5 is a side elevation, partially in section, of a helical coil, completely formed and ready for cutting into arcuate segments; and

FIG. 6 is a partial vertical section taken along the line 6-6 of FIG. 5.

Referring more particularly to the embodiment of the invention shown in FIGS. 1 and 2 of the drawings, reference numeral 10 represent one of the arms of a multiple armed gas burner head such as that of a gasoline field range outfit of the type used by the military forces, but modified in accordance with the present invention. The burner head, including arm 10 thereof, comprises a base member 11 having a generally U-shaped cross-section which is cast in one piece and comprises a central plenum chamber 12 and several arms similar to arm 10 which branch out in various directions from the plenum chamber 12 so that a relatively large area can be rapidly heated with the burner as gasoline vapors are fed into the plenum chamber and thence into the several arms of the burner head. Over the open top of each U-shaped arm is mounted an arcuate member 13 made in accordance with the invention and having a plurality of spaced slots 14 of substantially uniform width through which gas may pass to a combustion zone above the burner when the burner is operating. The plurality of spaced slots in each arm and plurality of arms in the burner head produce good mixing of the gas with air for effective combustion and heating over a large surface. Arcuate member 13 is detachably clamped on the open top of U-shaped base member 11 by means of clamps 15 which are L-shaped in cross-section and are mounted on the sides of base member 11 by means of bolts 16.

The outer end of U-shaped base member 11 has an end wall 17 which is preferably cast integrally therewith. Thi end wall may take a variety of shapes to provide a closure at the end of the arm. As shown in FIG. 1, the end wall 17 extends upwardly to the same height as the side walls of the arm and a first end plate 18 is detachably mounted on the end wall 17 by means of bolt 19. The upper portion of end plate 18 is formed to engage the outer end of arcuate member 13 to substantially seal the end of the arm 10. Also, in order to prevent excessive escape of gas at the inner end of arcuate member 13 a second end plate 20 is mounted bet-ween the inner end of arcuate member 13 and the outer wall of plenum chamber 12. This end plate may be held in place by friction or by means of one or more bolts (not shown).

Other means may be employed for the prevention of excessive escape of gas at the inner and outer ends of the arm. For example, the casting of the burner head may include an extension of end wall 17 which would snugly engage the outer end of arcuate member 13 and the sides and height of plenum chamber 12 may be conformed so that the inner end of arcuate member 13 may be brought into sufficiently tight engagement therewith to form a suitable closure.

I will now proceed to describe the method of the invention whereby a detachable arcuate member 13 having a plurality of spaced slots of substantially uniform width is produced and mounted on a base member having means for conducting gas to the plurality of spaced slots. In one embodiment of the invention a cylindrical mandrel 21 as shown in FIGS. 3 and 4 is employed for forming a helical coil 22 having an internal diameter substantially equivalent to the outside diameter of the mandrel. The coil is formed of metal strip having a rectangular cross-section in such manner that adjacent turns of the helical coil will be substantially uniformly spaced a predetermined amount which is suitable for the slots in a gas burner head. The dimensions of the metal strip may be varied depending on the desired spacing of the slots, the desired depth of the slots, the strength of the metal and other considerations. When mild carbon steel strip is used, a strip about As-inch thick and -inch wide has been found suitable. It will preferably be nickel plated all over to about 0.00005 inch plating thickness for a purpose to be described.

The mandrel 12 upon which the helical coil is formed is provided with four parallel channels 23 running longitudinally of the mandrel and spaced uniformly around the circumference thereof. Channels 23 are sized to receive straight metal bars 24 in each channel. Mild carbon steel strip approximately -inch thick and /z-inch wide has been found suitable as a material for bars 24. It is preferably nickel plated similarly to the metal strip of coil 22. The channels 23 and bars 24 are sufliciently long to extend beyond each end of the helical coil 22 after the forming thereof on the mandrel has been completed with the bars 24 in place in the channels 23. When a sufiicient number of turns of the helical coil have been formed on the mandrel, the end turn at each end of the coil 22 is spot welded to each of the four straight metal bars 24. The coil, attached by spot welds at each end to each of the four straight metal bars 24 is preferably removed from the mandrel for further processing.

After a brazing paste is applied to each of the turns of the helical coil 23 where it contacts each of the four straight metal bars 24, the coil with bar in place is placed in a brazing furnace and the brazing of the coil to the bars at each point of contact is carried out at about 1900-2000 F. or other suitable conditions for the selected brazing material. At the same time, the nickel plating is alloyed with the steel of the coil and bars, making the steel corrosion resistant and, therefore, much more durable than the cast burner heads of the prior art. The brazed coil 22 and bars 24 are then cut off at both ends so as to square the ends of the coil and remove any projecting portions of the metal bars. The coil 22 is then cut into four substantially equal arcuate members 13 by cutting the bars 24 and the individual turns of the coil along a line running the full length of each of the straight metal bars 24. Each of the resulting four arcuate members 13 is suitable for use as the slotted top of a gas burner head arm and ready for mounting on a base member in the manner previously described.

In FIGS. 5 and 6 there is shown a modified form of helical coil 22 which may be produced by either of two different procedures. In the first of these procedures, the metal strip is wound upon a mandrel 21 such as that shown in FIG. 3, the coil being wound to provide somewhat less spacing between adjacent turns than is desired as a final result. The metal strip is spot welded to each of four straight metal bars 24 at one end of the coil, preferably the end thereof nearest the free end of the mandrel. Then a wire 25 having a diameter equal to the desired width of the slots in the gas burner head is wound around the straight metal bars and between adjacent turns of the metal strip of the coil, thereby forcing the adjacent turns of the coil apart a distance equal to the diameter of the wire. As the wire 25 is being wound around the bars 24, the coil is gradually withdrawn from the free end of the mandrel so that the wire can be drawn reasonably taut about the bars 24 as shown in FIG. 6. Since the ends of bars 24 extend beyond the ends of the coil, they remain engaged in channels 23 in the mandrel when the coil itself has been completely withdrawn from the mandrel. The mandrel will therefore support bars 24 in position relative to the coil until the free end of the coil can be spot welded to each of the four bars. The coil may then be completely removed from the mandrel and brazed in a brazing oven in the same manner as previously described, squared at the ends, and cut into four equal arcuate members in the manner previously described. Since the wires will not significantly interfere with the flow of gas to the slots in the arcuate members, it is not necessary to remove them, although, if desired, the chordal portions of wire may be cut or otherwise removed from the arcuate members prior to mounting the same upon the base members of the gas burner head arms.

In the second procedure employed in making the modified form of helical coil 22 shown in FIGS. 5 and 6, the metal strip from which the helical coil is formed is wound upon a mandrel 21 such as that shown in FIG. 3 so that the adjacent turns of the coil are spaced somewhat farther apart than is desired as a final result. Again, the metal strip is spot welded to each of the four straight metal bars at one end of the coil, preferably the end nearest the free end of the mandrel. Then a wire 25 having a diameter equal to the desired width of the slots in the gas burner head being made is wound around the straight metal bars 24 and between adjacent turns of the metal strip of the coil. As in the first procedure for producing this modified form of the invention, it is preferred to gradually with draw the coil from the free end of the mandrel while winding the wire around the straight metal bars. After the winding of the wire is completed, the coil is compressed so that the spacing between adjacent turns thereof is reduced to the diameter of the wire. When all of the turns of the coil have been properly spaced, the end turn is spot welded as described previously, the coil is removed from the mandrel, brazed, squared at the ends and cut into four equal arcuate members in the manner previously described for the other modifications of the invention.

It may be preferred to remove the coil from the mandrel after it is wound thereon and spot welded at one end to each of the four straight metal bars to facilitate the winding of the wire and the proper spacing of the turns of the coil in either of the above modified procedures. A suitable jig or fixture will be required to main:

tain the bars in proper alignment until the winding and spacing are completed and the other end of the coil is spot welded to the bars. The important aspect of the procedures for making these detachable slotted arcuate memhers is that the turns of the helical coil be substantially equidistantly spaced throughout the length of the coil and that the individual turns of the coil be firmly joined to the straight metal bars at each crossover area. Then, when the helical coil is cut into four arcuate members, the cut portions of the individual turns of the coil will be firmly attached to the cut portions of the straight metal bars and the width of the slots will be maintained quite uniform throughout the useful life of the gas burner head.

The present invention provides a simple and relatively low-cost method of making slotted gas burner heads which have uniformly spaced slots, are corrosion resistant, and in which the top portion containing the slots is easily detachable and replaceable when necessary. Because of the corrosion resistance of the slot bounding surfaces, cleaning is not required nearly so often as in the cast and machined burner heads of the prior art. The overall cost of making and maintaining slotted gas burner heads in an efficient operating condition is greatly reduced by the present invention.

It will be understood that various changes in the details, materials of construction, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. The method of making a gas burner head having a plurality of spaced s ots in the upper surface thereof comprising forming a helical coil of predetermined diameter of metal strip having a rectangular cross-section,

said coil having a predetermined substantially uniform spacing between adjacent turns thereof,

mounting a plurality of straight metal bars longitudinally of said coil in spaced parallel relation, joining said bars to each turn of said coil,

cutting said coil and said bars longitudinally of said bars to form a plurality of arcuate members having a plurality of spaced slots of substantially uniform width, and

mounting said arcuate members on a base member having means for conducting gas to said slots.

2. The method of making a gas burner head as in claim 1 wherein said coil is formed by winding said strip on a circular mandrel having a plurality of longitudinal channels in spaced parallel relation in the outside surface thereof, said channels being adapted to receive said straight metal bars therein.

3. The method of making a gas burner head as in claim 1 wherein said straight metal bars are mounted on said coil by fixing the ends of said bars to one end of said coil, winding said bars with a continuous wire of predetermined diameter between the turns of said coil, compressing said coil end to end thereof, and fixing the other end of said bars to the other end of said coil whereby the space between adjacent turns of said coil conforms to the diameter of said wire.

4. The method of making a gas burner head as in claim 1 wherein said straight metal bars are joined to each turn of said coil by brazing.

5. The method of making a gas burner head as in claim 4 wherein said metal strip and said metal bars are formed of nickel plated steel.

6. The method of making a gas burner head as in claim 1 wherein the ends of said coil are ground square before cutting said coil to form said arcuate members.

References Cited UNITED STATES PATENTS 1,642,426 9/ 1927 Risinger.

1,801,363 4/1931 Mueller 29-4l2 X 2,623,550 12/1952 Artoni 29-412 X 2,683,922 7/1954 Zion 29-412 2,828,532 4/1958 Taylor 29-157 JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner US. Cl. X.R. 

